I would strongly recommend reading the following book: http://www.amazon.com/Go-Alone-Streetwise-Secrets-Employment... It's very clear and accessible, and is aimed at people with domain knowledge but not business knowledge and experience. It's consistent with the excellent advice offered by others in this thread, in book length.

I'm getting my cofounders to read it now, I first read it 12 years ago, and I still think it's the single best introduction to business and sales skills I've seen, despite having read a LOT of such books before, during and since my MBA. Good luck with the business!